For almost two years now, iPhone users have been looking for portable battery options to increase the run times of their phones, and companies have developed various solutions ranging from cabled battery packs to form-fitting backpacks and hybrid cases with batteries inside. They've ranged in price from $40 to $100, depending on features, and offered to extend iPhone or iPhone 3G longevity by up to three times. The latest option, Konnet's PowerKZ ($80), is a middle-of-the-pack alternative on features, pricing, and design, with one novel feature that will be of interest to many users.

Like Incase’s Power Slider for iPhone 3G, PowerKZ combines a case with a rechargeable Lithium-Polymer battery pack, using a design that fully covers the iPhone’s front bezel, thickens its back, and extends its bottom by roughly half an inch; unlike Power Slider, PowerKZ is made from a combination of glossy white or black plastic and chrome accents, physically fits* either the original iPhone or iPhone 3G, and features a full-sized Dock Connector port at the bottom for charging rather than the mini-USB port selected by Incase. While the Dock Connector port initially seems like a smart enough idea, it’s actually not so bright in practice: PowerKZ is too big to fit into Apple’s Universal Docks, so you’ll most likely charge it by occupying the Apple cable that came with the iPhone 3G. This is the rare situation in which a simple USB cable would have made more sense.

From the standpoints of functional and aesthetic design, PowerKZ is a step or two down from Power Slider, which in typical Incase fashion was polished to feel fully worthy of Apple’s own products. PowerKZ has some cheap-looking seams and poorly made pass-through button covers—one of the button covers actually came off after only light use—plus headphone and ringer switch holes that aren’t friendly to big fingers or headphones. At the bottom of the case are hole-like grilles for the speaker and microphone, plus a four red-LED charge level indicator and a button that serves either as a power switch or a way to see what the current power level is. Power is handled intelligently, turning itself off after 20 seconds pass without a connected iPhone 3G drawing power.

One of PowerKZ’s features is a real benefit for fans of widescreen video or other iPhone applications: a simple, low-profile video kickstand. Made from plastic, the stand pops out from the back of the case and places the iPhone on a great angle for viewing, a feature that more of these battery backpacks should really include. On the flip side, the case includes no screen protection, and drops the iPhone 3G’s 3G network performance by about a bar, with an equivalent or greater hit on EDGE signaling. Separately, speakerphone performance was described by our callers as poor, with significant echo-like feedback when they talked, and a muffling of our voices when we talked. The speaker is fine, however, for video and audio playback. We’ve seen similar issues in other battery cases; you’ll need to decide whether these factors matter to you.

The last major factor worth noting is PowerKZ’s battery life: the 1800mAh cell inside is capable of fully recharging an iPhone 3G once with extra juice to spare, which is actually better than what Power Slider offered, and comparable to the original MiLi Power Pack for iPhone, which sells for a similar price. That having been said, we had problems getting PowerKZ to charge an original iPhone, even after we tried a number of times to get the iPhone to seat more deeply on the Dock Connector inside; it fit but didn’t seem as secure as with the iPhone 3G, which fit better. Whether this is a molding issue or something else, the PowerKZ’s issue here—not explained in the included instruction manual—negated one of its possible selling points relative to other batteries out there.

At this point, it’s worth noting that companies such as FastMac offer iPhone model-agnostic battery alternatives with considerably higher power capacity at a slight premium, while Just Mobile’s caseless batteries with more capacity can be had for much less. Power Slider was unusually expensive given its low battery capacity, and even the MiLi backpack has been upgraded with a higher-capacity cell since its release.

Given its combination of features, capacity, design, and pricing, Konnet’s PowerKZ falls a bit short of recommendability as an iPhone 3G battery pack, and we’d actively recommend against considering it as a first-generation iPhone power alternative. While PowerKZ is benefitted by a nice video stand feature, a semi-protective design, and a fair overall price, it’s held back by some execution issues in its case design, as well as its approaches to recharging and speakerphone functionality. Normally, it would be been on the fine edges of B and B- ratings for the iPhone 3G given the price, but the easily broken volume button cover dropped it a full letter grade into C territory. With additional polish, an updated version might be worth considering.

Editors' Note: iLounge only reviews products in "final" form, but many companies now change their offerings - sometimes several times - after our reviews have been published.
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